Handle pending actions within screenshot action provider

Bug: 329659738
Test: manual (tested that share/edit actions work if tapped either
before or after screenshot saved)
Test: atest DefaultScreenshotActionsProviderTest
Flag: ACONFIG com.android.systemui.screenshot_shelf_ui DEVELOPMENT

Change-Id: If51c4d1b5671e1f24a58f270ef21137f9b054ca7